Projects per year
Transition metal catalyzed cross-couplings are an important tool in the synthetic and industrial chemist’s toolbox for creating simple and complex molecules. Palladium is the most exploited metal for the catalysts but due to its price and toxicity, efforts are being directed towards finding other metals that can be used instead. Nickel is one metal that has been successful as a metal catalyst, but like another examined metal, cobalt, it is also toxic. In recent years, the focus has been on iron, a metal which is both abundant, cheap and non-toxic. The present dissertation describes the attempts to expand the conditions of the known cross-couplings to include homogeneous manganese catalysts. In chapter 2: Manganese Catalyzed N-Arylation - a literature reported procedure for N-arylations through a non-cross-coupling mechanism was explored. The reaction proved hard to control (see graphical abstract) and gave no insights into manganese catalysis. In chapter 3: Buchwald-Hartwig Catalyzed Cross-Couplings - a literature reported procedure was examined. It was not possible to reproduce the literature findings. Instead, the reaction was shown to be catalyzed by 10-100 ppm of a copper catalyst (see graphical abstract). In chapter 4: Manganese Catalyzed Stille Cross-Couplings - a literature reported procedure was examined. It was not possible to reproduce the literature findings. Instead, the reaction was shown to be catalyzed by 30 ppm of a palladium catalyst (see graphical abstract). In chapter 5: Manganese Catalyzed Kumada Cross-Couplings - a literature reported procedure was examined. The scope of this reaction was limited for the electrophile, which was attributed to an aryl radical anion intermediate that was indicated by a clock experiment (see graphical abstract). In chapter 6: Dimethyl Zinc Mediated Radical Alkylation of β-Bromostyrenes - the attempts at a manganese catalyzed Negishi cross-coupling resulted in the discovery of a radical coupling of β-bromostyrenes with ethers and tertiary amines. (see graphical abstract).
|Publisher||Technical University of Denmark|
|Number of pages||149|
|Publication status||Published - 2017|